Option Explicit

Private Type NOTIFYICONDATA
    cbSize As Long
    hWnd As Long
    uID As Long
    uFlags As Long
    uCallbackMessage As Long
    hIcon As Long
    szTip As String * 64
End Type
   
Private Declare Function Shell_NotifyIcon Lib "shell32" Alias "Shell_NotifyIconA" (ByVal dwMessage As Long, lpData As NOTIFYICONDATA) As Long

Private Const NIM_ADD = &H0
Private Const NIM_MODIFY = &H1
Private Const NIM_DELETE = &H2

Private Const NIF_MESSAGE = &H1
Private Const NIF_ICON = &H2
Private Const NIF_TIP = &H4

Public Const WM_MOUSEMOVE As Long = &H200
Public Const WM_LBUTTONDOWN As Long = &H201
Public Const WM_LBUTTONUP As Long = &H202
Public Const WM_LBUTTONDBLCLK As Long = &H203
Public Const WM_RBUTTONDOWN As Long = &H204
Public Const WM_RBUTTONUP As Long = &H205
Public Const WM_RBUTTONDBLCLK As Long = &H206

Private NID As NOTIFYICONDATA

Public Sub Add(ByVal MyForm As Form, Optional ByVal sToolTip As String)
On Error GoTo ErrHandler
    With NID
        .cbSize = Len(NID)
        .hWnd = MyForm.hWnd
        .uID = vbNull
        .uFlags = NIF_MESSAGE Or NIF_ICON Or NIF_TIP
        .uCallbackMessage = WM_MOUSEMOVE
        .hIcon = MyForm.Icon
        If sToolTip <> vbNullString Then
            .szTip = sToolTip & vbNullChar
        End If
    End With
    Call Shell_NotifyIcon(NIM_ADD, NID)
    Exit Sub
ErrHandler:
    MsgBox "Could not add systray.", vbCritical, "Error"
End Sub

Public Sub Delete()
On Error GoTo ErrHandler
    Call Shell_NotifyIcon(NIM_DELETE, NID)
    Exit Sub
ErrHandler:
    MsgBox "Could not delete systray.", vbCritical, "Error"
End Sub

Public Sub Modify(ByVal MyForm As Form, Optional ByVal sToolTip As String)
On Error GoTo ErrHandler
    With NID
        .cbSize = Len(NID)
        .hWnd = MyForm.hWnd
        .uID = vbNull
        .uFlags = NIF_MESSAGE Or NIF_ICON Or NIF_TIP
        .uCallbackMessage = WM_MOUSEMOVE
        .hIcon = MyForm.Icon
        If sToolTip <> vbNullString Then
            .szTip = sToolTip & vbNullChar
        End If
    End With
    Call Shell_NotifyIcon(NIM_MODIFY, NID)
    Exit Sub
ErrHandler:
    MsgBox "Could not modify systray.", vbCritical, "Error"
End Sub